The progressive groups who unsuccessfully backed Bill Halter over Blanche Lincoln in the Arkansas Democratic Senate runoff on June 8 scored a victory tonight when Elaine Marshall defeated Cal Cunningham in North Carolina’s Democratic Senate primary. Marshall will now face first-term incumbent Senator Richard Burr in November.

Marshall-Cunningham did not have the prominence of Halter-Lincoln, nor were the ideological distinctions nearly as stark. But groups like Democracy for America and did rally behind Marshall in the final weeks of the race, to the dismay of the Democratic Senatorial Campaign Committee and the Democratic political establishment in Washington, which hand-picked Cunningham, an attorney, Iraq war vet and former state senator. Marshall was not exactly an outsider—having served as the state’s secretary of state for four terms, defeating NASCAR legend Richard Petty in her first race—but she ran as a progressive populist and grassroots advocate during the primary, playing up her opposition to the surge in Afghanistan and support for healthcare reform, including a public insurance option, and Wall Street reform. “The voters of North Carolina don’t like that someone is trying to anoint or elect their candidate,” Marshall said before the vote. Washington intervention has been a decidedly mixed blessing this election year, paying off in Democratic primaries in Arkansas and Ohio but backfiring in Pennsylvania and North Carolina. “The Democratic Party should welcome the competition of ideas,” says Jim Dean, chair of Democracy for America (DFA), “and not become an incumbency-protection racket.” Dean says the current clashes inside the party pit “a culture of activism versus a culture of incumbency.”

As has been well documented, it’s been a rough year for incumbents in both parties so far, even though Lincoln did squeak through in Arkansas (and now trails her Republican opponent, Congressman John Boozman, by thirty points). Halter’s loss obscured the excellent organizing work progressive groups did on his behalf. Arshad Hasan, DFA’s executive director, told me that Halter’s campaign exceeded its turnout targets for the runoff—yet so did Lincoln’s. Her base proved bigger than his. “What we need is a lot more and a lot better long-term organizing on the ground in places like Arkansas,” Hasan concluded after running Halter’s get-out-the-vote operation. Going forward, the Halter campaign, though ultimately unsuccessful, provides a framework for insurgent, outside-the-Beltway progressive engagement that can now be replicated and bolstered in other red and purple states, including in North Carolina, this fall. “If we want progressives in office, there’s never been a greater need for a fifty-state strategy,” Hasan says.

North Carolina should be a great test case for whether that strategy still has juice; Democrats won every major contested race there in 2008 and Barack Obama, surprisingly, carried the state by running a superb grassroots campaign. The political environment has become far less advantageous for Democrats since then, but last week the DNC announced a $50 million outreach effort to persuade first-time Obama voters—and register new ones—to vote Democratic in 2010. Turning out those voters—who were once inspired by Obama but retain questionable allegiance to the president and his party—will be critical to avoiding an electoral massacre in the fall. Marshall will go into the general election as an underdog, but in a tough year, her race could be an unlikely pickup opportunity for Democrats.